Stable aqueous emulsions



United States Patent 3,462,385 STABLE AQUEOUS EMULSIUNS Eugene S.Barabas, Watchung, and Frederick Grosser, Midland Park, N.J., assignorsto GAF Corporation, New York, N.Y., a corporation of Delaware NoDrawing. Filed Nov. 17, 1966, Ser. No. 595,026 e Int. Cl. C08f 21/00,43/00 US. Cl. 260-29.6 3 Claims ABSTRACT OF THE DISCLOSURE Stableaqueous emulsions of a graft terpolymer of a poly-N-vinyl lactam, suchas polyvinylpyrrolidone, upon which has been grafted ethylacrylate andhydroxyethyl methacrylate as side chains.

, The present invention relates, in general, to stable aqueous emulsionsand, in particular, to stable, aqueous emulsions comprising a graftedpolymeric N-vinyl lactam containing ethylacrylate and hydroxyethylmethacrylate.

Grafted polymers comprising a basic homopolymer chain containing graftedthereon units or a plurality of such units ofone'or more polymerizablemonomers, in chain form, grafted onto the basic homopolymer chainrepresent an interesting and important development in the resin. art s,particularly since such grafted polymers find immediate and practicalutility for the resin chemist to utilize them as building block resinsystems or module resin systems which can be employed to tailor-make s beguentresinsystems to, suitfispecific industrial needs.

Grafted copolymers can be made by a variety of polyme'r'ization methodsincluding solution, emulsion or bulk polymerization and the like. In thecase of polymeric N viiiylla'ct'am's, and particularly polyvinylpyrrolidone (poly-1-vinyl-2-pyrrolidone), their use has been limited toa great extent to those fields of utility which take advantage of theinherent physical characteristics of polyvinyl pyrrolidone, the mostimportant of which is its water solubility. While this physicalcharacteristic of water solubilityha's"projectedpolyvinyl pyrrolidoneinto a position of prominence for such industrial applications aspharmaceutical, cosmitic, textile, lithographic uses, it converselyprecluded their use in industrial applications where water-insolubilityof the resin system is a prerequisite."

' Accordingly, it is an object of this invention to providewater-insoluble compositions based on polymeric N-vinyl lactams.

Another object of this invention resides in the provision of stableaqueous emulsions of N-vinyl lactams.

Yet another object of this invention resides in the provision of stableaqueous emulsions comprising a grafted polymeric N-vinyl lactamcontaining ethylacrylate and hydroxyethyl methacrylate.

. Still another object of this invention resides in the provision ofstable aqueous emulsions comprising a grafted polymer of polyvinylpyrrolidone containing ethylacrylate and hydroxyethyl methacrylate.

Still other objects of the invention will become further apparent as thedescription of the invention proceeds.

I In accordance with the above-defined objects, methods have beendevised whereby stable aqueous emulsion latices are provided comprisingN-vinyl lactam containing ethylacrylate and hydroxyethyl methacrylate.

As a result of the invention upon which the present discovery is based,the latices of the present invention find immediate and practicalapplicability for use as cast films which are transparent, colorless andflexible. The films which are deposited are strong and clear and can beproduced directly upon evaporation at room temperatures.

3,462,385 Patented Aug. 19, 1969 Such materials are eminently useful asprotective coatings, impregnants and permanent sizing agents for paper,leather and the like. Still other useful applications of the emulsionsof the invention include their use as pastes or dispersions in hot dipcoating, slush casting and cellular elastomer applications.

The polymeric N-vinyl lactams utilized in the preparation of thecompositions of this invention are characterized by the followinggeneral structural formula:

wherein R represents an alkylene bridge group necessary to complete a 5,6 or 7-membered heterocyclic ring system, R represents either hydrogenor an alkyl group, and n. represents a number indicative of the extentof polymerization.

All of the specific polymeric materials characterized by the foregoinggeneral formula are commercially available and called polymeric N-vinyllactams. They are obtained by polymerizing organic 5, 6 or 7-memberedring ompounds containing in their rings the -NHCO-group, such as, forexample, 1-vinyl-2-pyrrolidone, 1-vinyl-5- methyl-Z-pyrrolidone,l-vinyl-Z piperidone, N vinyl ecaprolactaim, and the like. Dependingupon the extent of polymerization, polmers having molecular weightsranging from at least 400 up to 2,000,000 or more may be produced.Viscosity measurements are commonly used as an ""indi'cation' of theaveragemolecular' weight of polymeric compositions, the instant polymersbeing characterized by 'a chain of carbon atoms to which the lactamrings are attached through theirnitrogen atoms: I T T CHOHzCHCH2-CHCHrThe K value (Fikentscher) of any particular mixture of polymers iscalculated from viscosity data and is useful as an indication of theaverage molecular weight of such mixture. Its determination is fullydescribed in Modern Plastics, 23, N0. 3, 157-61, 212, 214, 216, 218(1945), and is defined as 1000 times k in the empirical relativeviscosity equation:

am 1rel. 7510 c l+l.5kC

wherein C is the concentration in grams per hundred cc.

of polymer solution and 1 is the ratio of the viscosity of the solutionto that of pure solvent. The K values are reported as 1000 times thecalculated viscosity coefiicient' in order to avoid the use of decimals.For the purpose of the present invention, there may be employed thosepolymeric N-vinyl lactams having a K value of about 10 to 200,preferably of 30 to because of their viscosity at lower concentrations.

K values and specific viscositie (11 are interconvertible and arerelated through relative viscosity (1 Thus, when viscosity measurementsare taken on solutions which have a concentration of 1.00 gram ofpolymer per deciliter of solution at 25 C. (C=1), the relationships areas follows:

f'lrel "lsp+ Relative viscosity=specific viscosity plus one.

Relative viscosity =10[0.001K+0.000075K /(l+0015K)] Relative viscosity,specific viscosity and K are dimensionless, whereas inherent viscosityenrel) /C and intrinsic viscosity (the limit of inherent viscosity as Capproaches zero) have the dimensions of dilution, i.e., the reciprocalof concentration. Intrinsic viscosity and K are intended to beindependent of concentration.

The number of recurring polymer units enclosed by brackets in theforegoing general structural formula, indicated by n, or the extent ofdegree of polymerization, corresponds to a chain of roughly 4 to 20,000monomer units or more. In actual practice, a mixture of polymericmolecules, each containing a different number (n) of monomer units, isalways produced. The polymers are readily prepared by the proceduralsteps given in United States Patents 2,265,450; 2,317,804; and 2,335,454and in which working examples of all the species characterized by theabove formula are given and all of which are incorporated herein byreference to said patents.

While not wishing to be bound by any particular theory or mechanism ofreaction, it is believed that the arrangement of the monomeric units,that is, the ethylacrylate and hydroxyethyl methacrylate monomers is anessential part of the invention in relation to the polymeric N-vinyllactam. With respect to the terpolymers of the present invention, theunits of ethylacrylate and hydroxyethyl methacrylate are not situated inthe main polymer chain but rather they form a more or less alternatingside chain on the preformed polyvinyl pyrrolidone which forms theskeletal chain for the addition of the ethylacrylate and hydroxyethylmethacrylate units. The ratio of the polymeric N-vinyl lactam and thecomonomers can be 90 active agents include fatty acid soaps, fattyalcohol sulfates such as sodium lauryl sulfate, potassium laurylsulfate, etc., alkali metal salts of aromatic sulfonic acids, e.g.,sodium isobutylnaphthalene sulfonate, etc., sulfosuccinic esters,phosphate esters of polyethoxy alkylphenols "y-stearaminopropyl,dimethyl fi-hydroxyethyl ammonium chloride, and the like.

The emulsions can be compounded with additives such as pigments, salts,wetting agents, resins, waxes and the like, thus providing a widespectrum of products having wide industrial application.

It has also been found that stable emulsions of the class describedabove can be prepared without the use of emulsifying agents orprotective colloids, although it has been observed that it is preferableto add such materials to the emulsion recipe in order to obtain highconversions and greater stability of the resultant emulsions.

The following examples will serve to illustrate the practice of theinvention:

EXAMPLE I Into a four-necked, one liter resin kettle equipped with amechanical stirrer, thermometer for liquid temperature, dropping funnel,reflux condenser, gas inlet tube and sampling tube are placed water,polyvinyl pyrrolidone, Gafac RE-610 (phosphate ester of polyethoxyalkylphenol) and ammonium persulfate in the amounts reflected in Table I(attached) and maintained at a temperature of 25 C. Subsequently,ethylacrylate and hydroxyethyl methacrylate monomer are added dropwiseover the time increments and temperatures indicated in Table I, as wellas subsequent additions of ammonium persulfate.

TABLE I Ml. of ingredients added at- Amount Seed, 0 1 1% 2 2% 3% 5% 1224 Ingredients Gm. ml. Hours of Reaction Water 311.0 160.5 155.0 a 5 X iu"r"'tir"' 3'3 4) y roxye 1y 1118 may Ethylacrylato 126.0 135.2 0 49 3Gafac RE-BlO 6. 6 2 66. 0 66.0 (NH)2SzOg 0. 52 a 52.0 52. 00 (NH4)zSz0a0.07 7.0 3 0 3.0 1.0 Temperatnre,0 25 100 90 1 The mount of water usedfor making solutions is deducted. 2 Solution in water. 3 Added at 60 C.4 60.0 g. to 99/1. The ratio of ethylacrylate and hydroxyethylAnalytical results: methacrylate can be 99/1 to 1/ 99. Solids, percent40.0 For the preparation of the emulsions of our invention, 50Conversion, percent 100.0 the polymerizations must be carried out inaqueous dis- Brookfield tvisc. (cps) 119.0

persion, in the presence preferably of a water-soluble initiator such aspotassium persulfate, ammonium persulfate or similar initiators andadvantageously in the presence also of a surface-active agent. Thepreferred practice is to first prepare an aqueous solution containingthe polymeric N-vinyl lactam, initiator and the surface-active agent,heat the solution to the desired temperature, and then add the monomersin admixture dropwise to the reaction mixture, or add separatelydropwise and at such rate that the respective monomers are completelyadded at the end of any stated time period. After completion of theaddition of all of the monomers, the reaction mixture is then heated fora period up to several hours or more. The resulting stable aqueousemulsion contains the resinous interpolymers, above-defined, in the formof small particles measuring in diameterabout from 100 to 300millimicrons. If desired, an activating agent such as an alkali metalsulfite or bisulfite, e.g., sodium, potassium, etc., sulfites andmetabisulfites can be added to the polymerization reaction mixture inabout the same amount as the polymerization initiator in which caselower polymerization temperatures may be used. Chain regulators such ashexyl, cetyl, dodecyl, myristyl, etc., mercaptans can also be employedin the polymerizations. Suitable surface- It will be apparent that inplace of the polyvinyl pyrrolidone having a potential K value of 30employed in the foregoing examples, other polymeric N-vinyl lactams orpolyvinyl pyrrolidone having other degrees of polymerization may beemployed in practicing the present invention. We particularly prefer thecommercially available polymers of N-vinyl-a-pyrrolidone havingpotential K values of from about K15 to K which corresponds to averagemolecular weights as determined by the Osmometric Method (H. P. Frankand G. B. Levy, I. Polymer Sci. 10, 371 (1953)) of from about 10,000 inthe case of PVP K15 to about 360,000 in the case of PVP K90, PVP K30having an average molecular weight of about 40,000 and PVP K60 having anaverage molecular weight of about 160,000.

Reference in the specification and claims to parts, proportions andpercentages, unless otherwise specified, refer to parts, proportions andpercentages by weight,

Since it is obvious that numerous changes and modifications can be madein the above-described details without departing from the spirit andnature of the invention, it is to be understood that all such changesand modifications are included within the scope of the invention andthat the invention is not limited to the exemplary details set forth byway of example, except as set forth in the appended claims or asnecessitated by the effect of the prior art.

What is claimed is:

1. A stable emulsion comprising water and a graft in which ethylacrylateand hydroxyethyl methacrylate comonomers are grafted onto a polymer ofan N-vinyl lactam corresponding to the formula:

CH Glit -In wherein R represents an alkylene bridge group containingfrom 2 through 4 carbon atoms, R represents a member of the groupconsisting of hydrogen and alkyl and n represents a positive integerselected from the group consisting of 4 through 20,000.

References Cited UNITED STATES PATENTS 2,890,199 6/1959 McNulty et al.

2,922,768 1/1960 Mino et a1 260-885 X 3,214,498 10/1965 Bauer 260885 X3,244,658 4/1966 Grosser et al.

MURRAY TILLMAN, Primary Examiner H. ROBERTS, Assistant Examiner US. ClX.R. 260-885

